Generator motor and work machine

ABSTRACT

A generator motor connected to an output shaft of an engine mounted in a work machine includes a terminal box for connecting an exterior electric-power-supplying cable to the generator motor. The terminal box includes a casing having an inner space in communication with an inside of a housing of the generator motor. A casing of the terminal box is detachably provided to the housing of the generator motor.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to International Application No.PCT/JP2012/057678 filed on Mar. 26, 2012, which application claimspriority to Japanese Application No. 2011-077698, filed on Mar. 31,2011. The contents of the above applications are incorporated herein byreference in their entireties.

TECHNICAL FIELD

The present invention relates to a generator motor and a work machine,particularly, improvement in a generator motor connected to an outputshaft of an engine mounted in a work machine.

BACKGROUND ART

As a work machine, there has been known a hybrid construction machine inwhich an engine drives a generator motor and a hydraulic pump, wherebyan electric motor for an upper rotary body where a cab and the like areprovided is driven by electric power generated by the generator motorwhile a hydraulic actuator for an operating device and a hydraulic motorfor a traveling device are driven by a pressure oil from the hydraulicpump.

In the hybrid construction machine, the generator motor and an inverterare electrically connected to each other via an electric-power-supplyingcable. The generator motor and the inverter are connected to theelectric-power-supplying cable via respective connectors. Such a hybridconstruction machine has been known for an arrangement that a terminalbox is provided to a housing of the generator motor in order to housethe connector of the generator motor (see, for instance, PatentLiterature 1).

CITATION LIST Patent Literature(s)

-   Patent Literature 1 JP-A-2010-272254

SUMMARY OF THE INVENTION Problem(s) to be Solved by the Invention

The housing of the generator motor is formed with a cable-insertion holein which a conductive line from a stator coil of the generator motor isinserted. Through the cable-insertion hole, a conductive line is drawninto the terminal box. In this arrangement, in assembling the generatormotor, it is necessary to draw the conductive line from the stator coilinto the terminal box through the cable-insertion hole while housing astator in the housing.

However, in the generator motor disclosed in Patent Literature 1, sincethe terminal box is integrally casted with the housing of the generatormotor, the terminal box is unremovable from the housing. Accordingly,when the conductive line is drawn into the terminal box, drawing theconductive line is time-consuming because of disturbance by the terminalbox, so that a satisfactory assembly performance cannot be secured.

An object of the invention is to provide a generator motor having animproved assembly performance and a work machine in which the generatormotor is mounted.

Means for Solving the Problem(s)

According to an aspect of the invention, a generator motor connected toan output shaft of an engine mounted in a work machine includes: aterminal box for connecting an exterior electric-power-supplying cableto the generator motor, in which the terminal box includes a casinghaving an inner space in communication with an inside of a housing ofthe generator motor, and the casing of the terminal box is detachablyprovided to the housing of the generator motor.

In the above aspect of the invention, the casing of the terminal box ismade of a material having a lighter weight than that of a material forthe housing of the generator motor.

In the above aspect of the invention, the casing of the terminal box ismade of an anti-corrosive material or a surface of the casing is treatedwith a corrosion protection processing.

In the above aspect of the invention, the casing of the terminal box ismade of aluminium.

In the above aspect of the invention, the casing of the terminal boxincludes: a case detachably provided to the housing of the generatormotor; and a cover member for closing an inner space of the case with aseal member interposed between the cover member and the case, in whichthe casing is made of aluminium, and the cover member is made of a steelmaterial having a galvanized surface.

In the above aspect of the invention, an inside of the generator motoris cooled by a cooling medium, and the terminal box is attached to thegenerator motor at a position higher than the rotation shaft of thegenerator motor.

In the above aspect of the invention, the terminal box is attached tothe generator motor at a position lower than a top surface of thegenerator motor.

The generator motor in the above aspect of the invention furtherincludes a cable-insertion hole that communicates the inside of thegenerator motor with an inside of the terminal box; and a closing memberthat closes the cable-insertion hole except for the cable.

The generator motor in the above aspect of the invention furtherincludes, in addition to the cable-insertion hole, a communication holethat communicates the inside of the generator motor with the inside ofthe terminal box.

In the above aspect of the invention, the terminal box houses aconnector for connecting the exterior electric-power-supplying cable tothe generator motor; and, while the terminal box is provided to thehousing of the generator motor, the connector is disposed facingdownward and the electric-power-supplying cable is connectable to theconnector from underneath the connector.

In the above aspect of the invention, the terminal box houses aplurality of connectors for connecting the exteriorelectric-power-supplying cable to the generator motor; and, while theterminal box is provided to the housing of the generator motor, theplurality of connectors are juxtaposed in a direction of the rotationshaft of the generator motor.

According to another aspect of the invention, a work machine includes:working equipment; a hydraulic pump that drives the working equipment;and the generator motor according to the above aspect of the invention,in which the hydraulic pump is provided to the generator motor.

According to the above aspect of the invention, the terminal box forconnecting the exterior electric-power-supplying cable to the generatormotor is detachably provided to the housing of the generator motor.Accordingly, while the terminal box is kept detached from the generatormotor, the stator can be housed in the housing of the generator motorand the conductive line of the stator coil can be easily pulled out fromthe housing of the generator motor. Once the conductive line is pulledout, the pulled-out conductive line can be easily drawn into theterminal box. Accordingly, when the conductive line is drawn into theterminal box, disturbance by the terminal box is preventable, so that asatisfactory assembly performance can be secured.

Since the centroid of the generator motor is displaced from the rotationshaft toward the terminal box if the terminal box has a heavy weight,vibration caused by impact during travelling and impact from the workingequipment may be increased, or vibration caused by driving of the engineand the hydraulic pump may be increased.

According to the above aspect of the invention, since the casing of theterminal box is made of a material having a lighter weight than a weightof a material for the housing of the generator motor, the weight of theterminal box can be lighter than a weight of the terminal box integrallyformed with the housing of the generator motor. Accordingly, thecentroid of the generator motor can be brought toward the rotationshaft, so that vibration is suppressible.

According to the above aspect of the invention, since the casing of theterminal box is made of the anti-corrosive material or the surface ofthe casing is treated with a corrosion protection processing, generationof rust on an interior and an exterior of the casing can be inhibited.Accordingly, occurrence of short-circuit or grounding caused by rust onthe casing as well as corrosion of the casing are preventable.

According to the above aspect of the invention, since the cover memberof the terminal box is made of aluminium, the terminal box can besignificantly light-weighted as compared with an arrangement that theterminal box is made of, for instance, iron, which can greatlycontribute to suppression of vibration.

According to the above aspect of the invention, the cover material ofthe terminal box closes the inner space of the case with the seal memberinterposed between the cover material and the case. Here, since thecover member receives a counterforce from the seal member, the covermember needs to be rigid enough to resist deformation by thiscounterforce. Since the cover member is made of a steel material havinga galvanized surface, a sufficient rigidity can be secured andanti-corrosive performance against rust and the like can be secured.Moreover, the production cost of such a cover material is more reduciblethan that of the cover member made of aluminium. Further, since the caseis made of aluminium, the weight of the terminal box is reducible by aweight of the case. Accordingly, anti-corrosive performance of theterminal box can be improved and the weight thereof can belight-weighted.

According to the above aspect of the invention, since the inside of thegenerator motor is cooled by the cooling medium, a bearing, a statorcoil and the like in the generator motor can be cooled. In thisarrangement, since the terminal box is attached to the generator motorat a position higher than the rotation shaft of the generator motor, thecooling medium in the inside of the generator motor can be inhibitedfrom entering the terminal box through the communication portion betweenthe generator motor and the terminal box.

According to the above aspect of the invention, since the terminal boxis provided to the generator motor at a position lower than the topsurface of the generator motor, the terminal box can be inhibited fromprojecting upward beyond the generator motor. Accordingly, the terminalbox can be prevented from interfering with the devices, members and thelike provided above the generator motor.

According to the above aspect of the invention, since thecable-insertion hole that communicates the inside of the generator motorwith the inside of the terminal box is provided, the conductive linefrom the stator-coil of the generator motor and a signal line from thesensor of the generator motor can be drawn into the terminal box byinserting those lines into the cable-insertion hole. Accordingly, it isnot necessary to draw the conductive line and the signal line around theexterior of the generator motor, so that the conductive line and thesignal line can be protected from moisture and dust in the outside.Moreover, since the closing member for closing the cable-insertion holeexcept for the cable therein is provided, the cooling medium andmoisture in the generator motor can be inhibited from entering theterminal box.

According to the above aspect of the invention, since a cooling-mediumreturn hole in communication with the inside of the generator motor andthe inside of the terminal box is provided in addition to thecable-insertion hole, the cooling medium and moisture having entered theterminal box through the generator motor can be returned into thegenerator motor.

According to the above aspect of the invention, while the terminal boxis provided to the housing of the generator motor, theelectric-power-supplying cable is disposed facing downward and isconnectable to the connector from underneath the connector. In thisarrangement, the electric-power-supplying cable connected to theconnector extends downward along the generator motor from the terminalbox. Accordingly, since the electric-power-supplying cable can besuppressed from projecting beyond the generator motor, the generatormotor can be more freely disposed.

Moreover, since the connector is provided facing downward, moisture suchas water drops from the above is prevented from entering the terminalbox through the connector.

According to the above aspect of the invention, since the connectors inthe terminal box are juxtaposed in a direction of the rotation shaft ofthe generator motor, the terminal box can be prevented from beingenlarged in an in-plane direction orthogonal to the rotation shaft ofthe generator motor due to the arrangement of the connectors, so that asize of the terminal box in the orthogonal surface can be minimized.Accordingly, since the terminal box can be downsized, the weight of theterminal box can be reduced, thereby promoting the light-weightedgenerator motor. Moreover, since the centroid of the generator motor towhich the terminal box is provided can be brought toward the rotationshaft of the generator motor by reducing the weight of the terminal box,vibration of the generator motor and vibration of the engine to whichthe generator motor is connected can be suppressed. Further, sincedownsizing the terminal box suppresses the terminal box fromsignificantly projecting beyond the generator motor, the generator motorcan be more freely disposed.

According to the another aspect of the invention, the work machineproviding the above-described advantages of the invention can beobtained by including the generator motor. Moreover, the hydraulic pumpfor driving the working equipment of the work machine is provided to thegenerator motor. In this arrangement, although vibration caused bydriving of the hydraulic pump is transmitted to the generator motor,since the centroid of the generator motor can be brought toward therotation shaft by downsizing of the terminal box, vibration caused bydriving the hydraulic pump can be effectively suppressed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a hybrid hydraulic excavator accordingto an exemplary embodiment of the invention.

FIG. 2 shows an overall structure of a driving system of the hybridhydraulic excavator.

FIG. 3 shows an inner structure and arrangement of a rotary body of thehybrid hydraulic excavator.

FIG. 4 is a plan view of a generator motor mounted in the hybridhydraulic excavator.

FIG. 5 is a side view of each of the generator motor, an engine and ahydraulic pump.

FIG. 6 is a perspective view of a pump-side housing of the generatormotor.

FIG. 7 is a partially enlarged view of the pump-side housing.

FIG. 8 is a cross-sectional view taken along the line VIII-VIII of FIG.4.

FIG. 9 is a perspective view of a case of a terminal box.

FIG. 10 is a plan view of a support plate fixed to the terminal box.

FIG. 11 is a cross-sectional view taken along the line XI-XI of FIG. 5.

FIG. 12 shows the terminal box seen from a bottom thereof.

FIG. 13 is a cross-sectional view taken along the line XIII-XIII of FIG.11.

FIG. 14 is a perspective view of a plug to be connected to the terminalbox.

DESCRIPTION OF EMBODIMENT(S)

An exemplary embodiment of the invention will be described below withreference to the drawings. Note that components described below can becombined as needed.

1. Overall Structure

FIG. 1 shows a hybrid hydraulic excavator 1 serving as a work machineaccording to the exemplary embodiment. The hybrid hydraulic excavator 1includes a vehicle body 2 and working equipment 3.

The vehicle body 2 includes a carrier 21 and a rotary body 22 rotatablyprovided on the carrier 21. The carrier 21 includes a pair of travelingdevices 211. The respective traveling devices 211 are provided withcrawler belts 212. A later-described hydraulic motor 213 drives thecrawler belts 212, whereby the hybrid hydraulic excavator 1 travels.

The rotary body 22 includes a cab 23, a counterweight 24 and an engineroom 25. The counterweight 24 is provided for weight balance against theworking equipment 3 and is filled with weights. An engine hood 26covering the engine room 25 has a grid-like opening 261. A cooling airfrom the outside is taken in the engine room 25 through the opening 261.

The working equipment 3 is attached to a front center of the rotary body22 and includes a boom 31, an arm 32, a bucket 33, a boom cylinder 34,an arm cylinder 35 and a bucket cylinder 36. A base end of the boom 31is rotatably connected to the rotary body 22. A distal end of the boom31 is rotatably connected to a base end of the arm 32. A distal end ofthe arm 32 is rotatably connected to the bucket 33.

The boom cylinder 34, the arm cylinder 35 and the bucket cylinder 36 arehydraulic cylinders driven by hydraulic oil discharged from thehydraulic pump 6. The boom cylinder 34 actuates the boom 31. The armcylinder 35 actuates the arm 32. The bucket cylinder 36 actuates thebucket 33.

FIG. 2 shows an overall structure of a driving system of the hybridhydraulic excavator 1.

In FIG. 2, the hybrid hydraulic excavator 1 includes an engine 4 as adriving source. The generator motor 5 and a pair of hydraulic pumps 6,6are connected in series to an output shaft of the engine 4 and aredriven by the engine 4.

The hydraulic oil fed by pressure from the hydraulic pump 6 is suppliedto the working equipment 3 through a control valve 7, whereby theworking equipment 3 is hydraulically actuated. The carrier 21 isprovided with the hydraulic motor 213 for driving a sprocket to bemeshed with a crawler. The hydraulic oil from the hydraulic pump 6 issupplied to the hydraulic motor 213 through the control valve 7.

On the other hand, the generator motor 5 is connected to a power cable 9(an electric-power-supplying cable) through the terminal box 8. Thegenerator motor 5 and an inverter 10 are connected to each other throughthe power cable 9. One end of another power cable 9 is connected to theinverter 10 while the other end of the power cable 9 is connected to arotary electric motor 11 for driving the rotary body 22. Moreover, acapacitor 12 for storing electric power is connected to the inverter 10.Accordingly, electric power generated by the generator motor 5 issupplied to the rotary electric motor 11 or stored in the capacitor 12through the inverter 10. The rotary electric motor 11 drives the rotarybody 22 rotatably provided to a top of an undercarriage through areducer 11A having a planet gear mechanism and the like When the speedof the rotary body 22 is reduced during rotary movement, regenerativebraking causes the rotary electric motor 11 to generate electric power.This electric power is stored in the capacitor. The electric powercharged in the capacitor 12 is boosted by a booster 10A and is suppliedfrom the capacitor 12 through the inverter 10 to the rotary electricmotor 11 and the generator motor 5 for assisting the engine 4 indriving.

FIG. 3 shows an inner structure and arrangement of the rotary body 22.

In FIG. 3, the inverter 10 and the capacitor 12 are provided on avehicle front side of the rotary body 22. The rotary electric motor 11is provided in the center of the rotary body 22. The engine room 25 isprovided on a rear side of the rotary body 22. The counterweight 24 isprovided in a further rear of the engine room 25. In the engine room 25,the engine 4, the generator motor 5 and the hydraulic pump 6 arejuxtaposed along the counterweight 24. Since the engine 4, the generatormotor 5 and the hydraulic pump 6 are required to be disposed within alimited space of a vehicle such as the rotary body 22, and inconsideration of a power transmission efficiency, the engine 4, thegenerator motor 5 and the hydraulic pump 6 are preferably disposed suchthat rotation shafts thereof are aligned.

As shown in FIG. 4, the terminal box 8 is provided to an outer surfaceof a housing 51 of the generator motor 5. Specifically, the terminal box8 is fixed to the housing 51 at a position on the housing 51 near thecounterweight 24 and between the rotation shaft of the generator motor 5and an upper surface 51A of the housing 51. The terminal box 8 is formedas a separate body from the housing 51 of the generator motor 5 and isdetachably attached to the housing 51.

As shown in FIGS. 4 and 5, a muffler 13 is provided above the terminalbox 8. The muffler 13 is fixed to a top of the generator motor 5 througha bracket 13A. Thus, the terminal box 8 is surrounded by thecounterweight 24 and the muffler 13. On a bottom 813 of the terminal box8, a plugging/unplugging opening 813A for the power cable 9 is provided(see FIGS. 9 and 11), whereby one end of the power cable 9 can bedetachably connected to the terminal box 8 from underneath the terminalbox 8. The other end of the power cable 9 is extended downward from theterminal box 8 and connected to the inverter 10 while passing under theengine 4.

In this arrangement, an openable/closable under-cover is provided on abottom of the rotary body 22 under the engine 4. When the under-cover isopened, an operator or maintenance staff can squeeze his upper body intoengine room 25. Accordingly, for maintenance of devices in the engineroom 25, the power cable 9 can be easily plugged in or unplugged fromthe terminal box 8 through the bottom of the terminal box 8

2. Structure of Generator Motor

The generator motor 5, which is a three-phase SR (Switched Reluctance)motor, includes a separable housing 51 as shown in FIG. 5. The housing51 includes an engine-side housing 52 that is fixed to the engine 4 andhouses a flywheel 4A; and a pump-side housing 53 that is fixed to theengine-side housing 52.

The pump-side housing 53 has a circular opening toward the hydraulicpump 6. This opening is covered with a disc-like support member 54 (seeFIG. 6) that rotatably supports a rotor 56. By closing the opening withthe support member 54, the rotor 56 is housed in a stator 55, andsimultaneously, one end of a shaft provided in the rotation center ofthe rotor 56 is connected (e.g., splined) to an output shaft of theengine 4 or a member connected to the output shaft. The other end of theshaft is provided corresponding to a center hole of the support member54 and is splined or the like to an input shaft of the hydraulic pump 6through the center hole.

An oil reservoir 57 is provided in a lower part of the housing 51. Inthe oil reservoir 57, a cooling oil as a cooling medium is accumulated.The cooling oil in the oil reservoir 57 is circulated to an oil cooler57A (see FIGS. 4 and 6) through a filter and a pump (not shown) of anoutside pipe and is returned from the oil cooler 57A to an upper part ofthe pump-side housing 53. The cooling oil returned from the upper partof the pump-side housing 53 to the inside of the housing 51 flowsradially outward from the center of the rotation shaft because ofcentrifugal force while lubricating the splined portions among theoutput shaft of the engine 4, the rotor 56 and hydraulic pump 6, and abearing of the rotor 56. The cooling oil is splashed by the rotatingrotor 56 and flywheel 4A into mist to cool a stator coil 551 provided inthe stator 55. Subsequently, the cooling oil drops into the oilreservoir 57 from the cooled part of the stator coil 551.

FIGS. 6 and 7 show the pump-side housing 53.

In FIGS. 6 and 7, a fixing portion 531 for fixing the terminal box 8 isprovided at a fixing position of the terminal box 8 in the pump-sidehousing 53. The fixing portion 531 includes: a bolt hole 532 for fixingthe terminal box 8; a cable-insertion hole 533 in which the conductiveline 14 from the stator coil 551 is inserted (see FIG. 7); and an oilreturn hole 534 (i.e., communication hole) through which the oil fed inthe terminal box 8 through the cable-insertion hole 533 is returned tothe inside of the generator motor 5.

In this arrangement, sensors such as a temperature sensor that detects atemperature of the stator coil 551 and a rotation sensor that detects arotation speed of the rotor 56 of the generator motor 5 are provided tothe generator motor 5. A plurality of signal lines 15 from the sensorsare drawn into the terminal box 8 through the cable-insertion hole 533together with the conductive line 14 from the stator coil 551.

As shown in FIG. 7, a grommet 58 is fitted as a closing member in thecable-insertion hole 533. The grommet 58 is formed in separate parts ofa first member 581 and a second member 582. Flanges 583 and 584 arerespectively formed on edges of the first member 581 and the secondmember 582. Three insertion grooves 586 for inserting the conductiveline 14 and the signal lines 15 are formed on a contact surface 585 ofthe second member 582 in contact with the first member 581. While thegrommet 58 is fitted into the cable-insertion hole 533 of the pump-sidehousing 53 to close the cable-insertion hole 533 except for theconductive line 14 and the signal lines 15, a surface of the grommet 58is pressed by a press member 59. The press member 59 includes acable-insertion hole 591 for inserting the conductive line 14 and thesignal lines 15, and a notch 592 formed by cutting the press member 59at a position corresponding to the oil return hole 534 of the pump-sidehousing 53. The terminal box 8 in this arrangement is fixed to thefixing portion 531 of the pump-side housing 53.

3. Structure of Terminal Box

As shown in FIG. 8, the terminal box 8 includes: a casing 8A; sockets83A and 83B (connectors) that are housed in an inner space of the casing8A and to which the conductive line 14 from the stator 55 is connected;and a support plate 84 (support member) that supports the socket 83B, inwhich the sockets 83A and 83B are housed in a double-layer arrangementin the direction of the rotation shaft of the generator motor 5.

The casing 8A includes a case 81 having an inner space, and a covermember 82 that closes the inner space of the case 81. Each of the case81 and the cover member 82 is made of a material different from that forthe housing 51 of the generator motor 5. Specifically, the housing 51 ismade of cast iron, whereas the case 81 is made of aluminium(anti-corrosive material). On the other hand, the cover material 82 ismade of a steel material having a galvanized surface. A gap between thecase 81 and the cover member 82 is sealed by an O-ring 80 (sealingmember).

As shown in FIG. 9, the case 81 is shaped substantially in a pentagon ina side view. The case 81 includes: a fixing surface 811 that is fixed tothe pump-side housing 53; an upper surface 812 and a bottom 813 that arevertically opposed to each other when the terminal box 8 is fixed to thepump-side housing 53; a side surface 814 that is orthogonal to each ofthe fixing surface 811, the upper surface 812 and the bottom 813; and anopening 815 that is opposed to the side surface 814 with the inner spaceof the case 81 being interposed between the opening 815 and the sidesurface 814.

While the terminal box 8 is fixed to the pump-side housing 53, thefixing surface 811 is inclined relative to bottom 813 such that thebottom 813 is substantially horizontal. The fixing surface 811 has acable-insertion hole 811A that is in communication with thecable-insertion hole 533 of the pump-side housing 53 and through whichthe conductive line 14 and the signal lines 15 are inserted. By thecable-insertion hole 811A and the cable-insertion hole 533 of thegenerator motor 5, the inner space of the terminal box 8 is brought indirect communication with the inside of the housing 51 of the generatormotor 5. A flange 811B is formed around the cable-insertion hole 811A ofthe fixing surface 811. The flange 811B has a bolt hole 811C for fixingthe terminal box 8 to the pump-side housing 53.

On the bottom 813, two plugging/unplugging openings 813A for the powercable 9 are provided corresponding to the sockets 83A and 83B.Specifically, while the terminal box 8 is fixed to the pump-side housing53, the plugging/unplugging openings 813A are juxtaposed in thedirection of the rotation shaft of the generator motor 5. A projection813B is formed in a manner to project from an inner surface of thebottom 813. A distal end of the support plate 84 is brought into contactwith the projection 813B.

The side surface 814 is located near the engine 4 when the terminal box8 is fixed to the pump-side housing 53. On an inner surface of the sidesurface 814, a socket fixing portion 814A to which the socket 83A isfixed; a plate fixing portion 814B to which the support plate 84 isfixed; a conductive-line holder 814C to which a holding bracket 85 (seeFIG. 11) for the conductive line 14 is fixed; and a signal-line holder814D to which a holding bracket 86 (see FIG. 11) for the signal lines 15is fixed.

The socket fixing portion 814A is provided closer to the bottom 813 thanthe plate fixing portion 814B of the side surface 814 is and is in astep-up shape from the inner surface of the side surface 814. The socketfixing portion 814A has a bolt hole 814E for fixing the socket 83A.

The plate fixing portion 814B is provided opposite to the bottom 813with the socket fixing portion 814A interposed therebetween. The platefixing portion 814B is shaped in a cylinder having a height from theinner surface of the side surface 814 larger than a height of the socketfixing portion 814A.

The conductive-line holder 814C is positioned closer to the uppersurface 812 and closer to the fixing surface 811 than the plate fixingportion 814B is. The conductive-line holder 814C is shaped in acylindroid having a height from the inner surface of the side surface814 smaller than the height of the plate fixing portion 814B.

A plurality of signal-line holders 814D are provided to the side surface814. One of the signal-line holders 814D is shown in FIG. 9. Thesignal-line holders 814D are positioned so as to surround the socketfixing portion 814A, the plate fixing portion 814B and theconductive-line holder 814C from near the upper surface 812.

The opening 815 is open toward the hydraulic pump 6 when the terminalbox 8 is fixed to the pump-side housing 53. An O-ring groove 816 for theO-ring 80 is provided on the periphery of the opening 815.

As shown in FIG. 10, the support plate 84 includes a narrow part 841 anda wide part 842. A width of the narrow part 841 is smaller than a widthof the wide part 842. Bolt holes 841A for fixing the socket 83B areformed on both sides of the narrow part 841 in a width direction. Acontact end 841B in contact with the projection 813B of the case 81 isprovided at an end of the narrow part 841. On the other hand, bolt holes842A for fixing the support plate 84 to the plate fixing portion 814B ofthe case 81 are formed on both sides of the wide part 842 in a widthdirection.

As shown in FIGS. 8 and 11, the socket 83A (83B) includes a metallicL-shaped bracket 831 and a resin-made receptacle 832 fixed to thebracket 831. The socket 83A (83B) is fixed to the case 81 by a bolt tobe inserted through a bolt hole of the bracket 831. The receptacle 832is divided by the bracket 831 fixed thereto into a first part and asecond part. A terminal 833 to which the conductive line 14 from thestator 55 is connected is provided in the first part while three holders834 in which a later-described plug 90 of the power cable 9 are fittedare provided in the second part. A metallic and conductive socketcontact 835 in a cylindrical shape is buried in each of the holders 834.The socket 83A (83B) is disposed in the terminal box 8 such that thesocket contact 835 faces downward.

As shown in FIG. 12, the socket 83A (83B) includes a contact terminal836 serving as a part of an interlock switch for detecting a connectingcondition between the terminal box 8 and the power cable 9. The contactterminal 836 is made of an elastic metallic member shaped in a platespring. The contact terminal 836 is provided to a resin-made supportmember 837 fixed to the bracket 831 and is electrically connected to theinverter 10 through a signal line 15A. While the plug 90 is properlyfitted in each of the sockets 83A and 83B, a later-described contactconductor 971 (see FIG. 14) of the plug 90 is automatically brought intocontact with the contact terminals 836 of the sockets 83A and 83B toelectrically communicate the contact terminals 836 with each other.Moreover, in this condition, since each of the contact terminals 836 ispressed by the contact conductor 971 to be elastically deformed, mutualcontact condition is kept favorable by elastic force of the contactterminals 836.

In order to dispose the sockets 83A and 83B in a double-layerarrangement within the terminal box 8, the socket 83A is bolted to thesocket fixing portion 814A of the case 81, and then, the support plate84 is bolted to the plate fixing portion 814B. Subsequently, the socket83B is bolted on the fixed support plate 84, so that a pair of sockets83A and 83B are disposed in a double-layer arrangement with the supportplate 84 interposed therebetween.

Meanwhile, a detector of the inverter 10 outputs a detection pulse fordetecting a fitting condition through the signal line 15A. Thisdetection pulse passes through the contact terminal 836 and the contactconductor 971 (see FIG. 14) and returns to the inverter 10 through thesignal line 15A. When the returned detection pulse is detected by thedetector for detecting pulse waves, the detector being provided in theinverter 10, it is determined that the plug 90 is properly fitted ineach of the sockets 83A and 83B.

For instance, when the socket 83B is fixed to the plug 90 in a manner tobe too close to the upper surface 812, or when the socket 83B isdiagonally fixed to the plug 90 relative to an axial direction of theplugging/unplugging opening 813A, contact failure may occur between thecontact terminal 836 of the socket 83B and the contact conductor 971 ofthe plug 90 and between the socket contact 835 and a later-described pincontact 95 of the plug 90. In this case, since the contact conductor 971is not properly in contact with the contact terminals 836 of the sockets83A and 83B, a detection pulse neither returns to the inverter 10 nor isdetected by the detector. Accordingly, the fitting between the sockets83A, 83B and the plug 90 is determined to be incomplete or completelyapart, so that a fail-safe processing such as deactuating of the hybridhydraulic excavator 1 is carried out. In order to prevent such anerroneous detection, positioning of the sockets 83A and 83B in theterminal box 8, particularly, positioning of the socket 83B fixed to thecase 81 through the support plate 84 becomes crucial.

Accordingly, the socket 83B placed on the support plate 84 is fixed tothe support plate 84 after the support plate 84 is positioned in thecase 81. Specifically, as shown in FIG. 13, the support plate 84 isfixed to the plate fixing portion 814B of the side surface 814 while thecontact end 841B is brought into contact with the projection 813B of thebottom 813 along a direction in which the power cable 9 is attached ordetached. Thus, the support plate 84 is positioned in a top-and-downdirection in the figure and in a direction orthogonal to the paper. Inother words, the bolt hole 814E provided in the socket fixing portion814A of the case 81 and a bolt hole 841A provided near the contact end841B of the support plate 84 are equidistant from theplugging/unplugging opening 813A, so that the sockets respectively fixedto bolt holes 814E and 841A becomes aligned. Thus, by fixing the socket83B to the support plate 84 already positioned in the terminal box 8,the socket 83B is properly positioned in the terminal box 8.

4. Structure of Plug of Power Cable

As shown in FIG. 14, the plug 90 includes: a conductive plug housing 91through which three power cables 9 are inserted; and a metallic plate 92that covers an opening on a front (opposite to a side where the cablesare inserted) of the plug housing 91.

The plug housing 91 includes: a contact portion 911 that is brought intocontact with an exterior of the case 81 of the terminal box 8 when theplug 90 is fitted in the sockets 83A and 83B of the terminal box 8; anda projection 912 that is formed in a manner to project from the contactportion 911 and is inserted into the plugging/unplugging opening 813A ofthe terminal box 8.

The contact portion 911 includes a seal ring 93 that surrounds theprojection 912. When the plug 90 is fitted in the sockets 83A and 83B ofthe terminal box 8, a gap between the contact portion 911 and theexterior of the case 81 of the terminal box 8 is sealed by the seal ring93.

In the plug housing 91, a holder 94 is provided for each of the cables.The cables are inserted into the holders 94. The conductive pin contact95 is attached to a tip end of each of the cables inserted into theholders 94 and projects from a round hole formed in each of the holders94.

The plate 92 is fixed to the plug housing 91 by a plurality of screws921. Both front and back surfaces and circumferential end surfaces ofthe plate 92, an inner circumferential surface of an insertion hole forthe screws 921, and an inner surface of an opening for inserting theholder 94 are entirely covered with insulating coating. For insulatingcoating, for instance, a fluorine coating is employed in view of heatresistance, wear resistance and water repellency. Due to this insulatingcoating, the plate 92 becomes insulated against the plug housing 91electrically grounded.

A conductive terminal 97 is fixed to the front surface of the plate 92through an insulative plate 96 made of a glass-epoxy composite material.The insulative plate 96 and the conductive terminal 97 are fixed to theplate 92 by the above-described screws 921. A material for theconductive terminal 97 only needs to be conductive. Although thematerial is not limited, brass is used in the exemplary embodiment.

The contact conductor 971, which is shaped in a quadrangular piecefolded in a fitting direction to the sockets 83A and 83B, is integrallyprovided to the conductive terminal 97. As described above, the contactconductor 971 is a portion in contact with the contact terminals 836 ofthe sockets 83A and 83B when the plug 90 is fitted in the sockets 83Aand 83B.

The conductive terminal 97 is coated with insulating coating in the samemanner as the plate 92, except for a contact area (i.e., contactconductor 971) in contact with the contact terminal 836. Accordingly,not only the insulative plate 96 enables insulation between the plate 92and the conductive terminal 97, but also the insulating coating of theplate 92 and the conductive terminal 97 further ensures insulationtherebetween, resulting in reliable insulation between the conductiveterminal 97 and the plug housing 91.

In the plug 90 as arranged above, the contact portion 911 of the plughousing 91 has a bolt hole 913 for fixing the plug 90 to the terminalbox 8. The plug 90 is fixed to the case 81 of the terminal box 8 by abolt 914 inserted through the bolt hole 913. Here, a bolt slipprevention member 915 in a form of a ring made of rubber, resins and thelike is fitted in a screw part of the bolt 914. The bolt slip preventionmember 915 prevents the bolt 914 from slipping off the plug 90.

5. Operations and Advantages of Embodiment(s)

In the hybrid hydraulic excavator 1 as arranged above, since thelarge-sized generator motor 5 having a large capacity is used, forinstance, a weight of the stator 55 becomes extremely heavy as comparedwith that in an automobile. However, since the case 81 of the terminalbox 8 is detachably provided to the pump-side housing 53 of thegenerator motor 5, while the terminal box 8 is kept detached from thepump-side housing 53, the stator 55 can be housed in the pump-sidehousing 53 of the generator motor 5 and the conductive line 14 of thestator coil 551 can be easily pulled out through the cable-insertionhole 533. Once the conductive line is pulled out, the pulled-outconductive line can be easily drawn into the terminal box, so that asatisfactory assembly performance can be secured.

Moreover, since the terminal box 8 is made of a material having alighter weight than that for the housing 51 of the generator motor 5,the centroid of the generator motor 5 can be brought toward the rotationshaft, so that vibration of the generator motor 5 and the engine 4directly connected to the generator motor 5 is suppressible.

Moreover, in the terminal box 8, since the plurality of sockets 83A and83B are juxtaposed in the direction of the rotation shaft of thegenerator motor 5, a size of the terminal box 8 in a plane orthogonal tothe rotation shaft of the generator motor 5 is reducible. Accordingly,the terminal box 8 is prevented from significantly projecting beyond thegenerator motor 5, so that the terminal box 8 can be more freelydisposed.

However, for instance, when air containing moisture or water drops enterthe terminal box 8 through the opening 261 of the engine hood 26 or thehousing 51 of the generator motor 5, the drops adhere on the terminals833 of the sockets 83A and 83B, the socket contact 835, the pin contact95 of the plug 90 of the power cable 9 and the like, anelectric-power-supplying line between the generator motor 5 and theinverter 10 may possibly be short-circuited or grounded. When themoisture adheres on the contact terminals 836 of the sockets 83A and 83Bor the contact conductor 971 of the plug 90, the signal line 15A maypossibly be short-circuited or grounded to cause an erroneous detection.Further, when the moisture adheres on the case 81 or the cover member82, the case 81 or the cover member 82 may possibly gather rust to causeshort circuit and grounding.

In contrast, in the terminal box 8, since the plugging/unpluggingopening 813A for the power cable 9 is provided on the bottom 813 of theterminal box 8, for instance, even when water or dust enter the engineroom 25 through the opening 261 of the engine hood 26, water dropsfalling from above can be prevented from entering the terminal box 8.Accordingly, short-circuit or grounding of the electric-power-supplyingline and the signal lines 15,15A can be prevented.

Moreover, since the case 81 of the terminal box 8 is made of aluminiumand the surface of the cover member 82 is galvanized, the terminal box 8can be suppressed from gathering rust. Accordingly, occurrence ofshort-circuit or grounding caused by rust as well as corrosion of thecase are preventable.

In the terminal box 8, while the case 81 is provided to an exterior ofthe generator motor 5, the sockets 83A and 83B are disposed facingdownward and one end of the power cable 9 is inserted into theplugging/unplugging opening 813A from underneath the terminal box 8 tobe connected to each of the sockets 83A and 83B. With this arrangement,the power cable 9 connected to the terminal box 8 extends downward alongthe generator motor 5 from the terminal box 8, but does not projectupward or sideward beyond the terminal box 8. Accordingly, for instance,even when the muffler 13 and the counterweight 24 are disposed near theterminal box 8, the power cable 9 can be prevented from interfering withthe muffler 13 and the counterweight 24. Moreover, since the power cable9 is opposite to the muffler 13 with the terminal box 8 interposedtherebetween, the power cable 9 is less likely to be affected by heat ofthe muffler 13, so that the power cable 9 can be prevented from beingdegraded by the heat.

As shown in FIG. 11, the inner surface of the terminal box 8 iscommunicated with the inside of the housing 51 through thecable-insertion hole 811A of the case 81 and the cable-insertion hole533 of the pump-side housing 53. Accordingly, the cable-insertion hole533 of the pump-side housing 53 is closed by the grommet 58 so as toprevent the mist-like cooling oil, which is obtained by being splashedin the housing 51, from entering the terminal box 8. Here, since theflanges 583 and 584 of the grommet 58 are locked on an edge of thecable-insertion hole 533, the grommet 58 is prevented from falling intothe cable-insertion hole 533 of the pump-side housing 53.

Although the housing 51 is sealed by the grommet 58 so as to avoid thecooling oil or moisture from leaking into the terminal box 8, a part ofthe cooling oil or moisture in a form of mist occasionally enter theterminal box 8 through the cable-insertion hole 533 and 811A. For thisreason, the oil return hole 534 for returning the oil and the moisturehaving entered the terminal box 8 to the generator motor 5 is providedin the pump-side housing 53.

The inner surface of the bottom 813 is inclined downward toward thepump-side housing 53 of the generator motor 5 only by a predeterminedangle α relative to a horizontal direction. With this arrangement, thecooling oil accumulated in the bottom 813 after entering the terminalbox 8 flows on the bottom 813 toward the pump-side housing 53. As shownin an arrow A, the cooling oil passes through the cable-insertion hole811A also serving as an oil return hole of the terminal box 8 andthrough the oil return hole 534 of the pump-side housing 53 and isreturned into the housing 51. Accordingly, the oil entering the terminalbox 8 can be returned into the housing 51 without accumulating in theterminal box 8.

It should be understood that the scope of the invention is not limitedto the above-described exemplary embodiment but includes modificationsand improvements as long as the modifications and improvements arecompatible with the invention.

Although the case 81 of the terminal box 8 is exemplarily made ofaluminium and the cover member 82 is exemplarily made of a steelmaterial having a galvanized surface in the exemplary embodiment, amaterial for the casing 8A of the terminal box 8 is not limited thereto.In short, it is only required that the casing 8A of the terminal box 8is detachably provided to the housing 51 of the generator motor 5. Forinstance, the case 81 and the cover member 82 may be made of resins, orthe entire casing 8A including the cover member 82 may be made ofaluminium.

Provided that the casing 8A of the terminal box 8 is detachable from thehousing 51 of the generator motor 5, the casing 8A may be made of thesame material as a material for the housing 51. For instance, the casing8A of the terminal box 8 and the housing 51 of the generator motor 5 areprovided by separate bodies formed by aluminium casting and the casing8A is detachably provided to the housing 51. In this arrangement, sincethe housing 51 of the generator motor 5 is made of aluminium, heatrelease performance of the generator motor 5 can be enhanced.

The casing 8A of the terminal box 8 is preferably made of ananti-corrosive material or a material whose surface is treated with acorrosion protection processing. For instance, the case 81 and the covermember 82 may be made of titanium.

In the exemplary embodiment, the cable-insertion hole 811A of theterminal box 8 also serves as the oil return hole. In addition to thecable-insertion hole 811A, the case 81 may have another oil return hole.Through the another oil return hole and the oil return hole 534 of thepump-side housing 53, the cooling oil having entered the terminal box 8may be returned into the housing 51.

In the exemplary embodiment, while the case 81 of the terminal box 8 isprovided the exterior of the generator motor 5, the sockets 83A and 83Bare juxtaposed in the direction of the rotation shaft of the generatormotor 5. However, the sockets 83A and 83B may be juxtaposed in anydirection. It is only required that the sockets 83A and 83B arejuxtaposed in a direction intersecting an orthogonal plane that isorthogonal to the rotation shaft of the generator motor 5. For instance,the sockets 83A and 83B may be juxtaposed in a direction diagonallyintersecting the orthogonal plane.

In the exemplary embodiment, the support plate 84 is used as a supportmember for supporting the socket 83B. However, the shape of the supportmember is not limited to that of the support plate 84. The supportmember only needs to support and position the socket 83B. The supportmember may be provided by a member having a shape other than aplate-shape.

In the exemplary embodiment, the grommet 58 is fitted in thecable-insertion hole 533 of the generator motor 5. However, forinstance, the grommet 58 may be fitted in the cable-insertion hole 811Aof the terminal box 8, or may be fitted in each of the cable-insertionhole 533 and the cable-insertion hole 811A. The grommet 58 is notessential. Accordingly, no grommet 58 may be arranged.

In the exemplary embodiment, the muffler 13 is fixed to the generatormotor 5. However, the location of the muffler 13 is not limited to this.For instance, the muffler 13 may be provided to the rotary body 22.

In the exemplary embodiment, the rotation shaft of the engine 4 and therotation shaft of the generator motor 5 are splined. However, a methodof connecting mutual output shafts is not limited to this. For instance,the output shaft of the engine 4 may be connected to the generator motor5 via PTO (Power Take Off).

In the exemplary embodiment, an SR motor is used for the generator motor5. However, the generator motor 5 is not limited to this. For instance,the invention may be applicable to a generator motor other than a PM(Permanent Magnet) motor and the like.

Although the exemplary embodiment describes when the invention isapplied to the hybrid hydraulic excavator 1, the invention may beapplicable to work machines such as a wheel loader, a bulldozer, a dumptruck and the like.

INDUSTRIAL APPLICABILITY

The invention is applicable to a work machine such as an earth-movingmachine, an agricultural machine, a driving vehicle and a deliveryvehicle other than a hybrid hydraulic excavator.

EXPLANATION OF CODES

1: hybrid hydraulic excavator (work machine), 3: working equipment, 4:engine, 5: generator motor, 6: hydraulic pump, 8: terminal box, 8A:casing, 9: power cable (electric-power-supplying cable), 51: housing,58: grommet (closing member), 81: case, 82: cover member, 83A, 83B:socket (connector), 533: cable-insertion hole, 534: oil return hole(communication hole)

The invention claimed is:
 1. A generator motor connected to an outputshaft of an engine mounted in a work machine, the generator motorcomprising: a terminal box for connecting an exteriorelectric-power-supplying cable to the generator motor, the terminal boxhaving a casing that defines an inner space in communication with aninside of a housing of the generator motor; wherein a cable-insertionhole enables communication between the inside of the generator motor andthe inner space, wherein a communication hole that is separate from thecable-insertion hole is provided at a position vertically below thecable-insertion hole, the communication hole enabling additionalcommunication between the inside of the generator motor and the innerspace, and wherein the casing of the terminal box is detachably providedto the housing of the generator motor at a position that is verticallyabove a rotation shaft of the generator motor.
 2. The generator motoraccording to claim 1, wherein the casing of the terminal box is made ofa material having a lighter weight than that of a material for thehousing of the generator motor.
 3. The generator motor according toclaim 1, wherein the casing of the terminal box is made of ananti-corrosive material or a surface of the casing is treated with acorrosion protection processing.
 4. The generator motor according toclaim 1, wherein the casing of the terminal box is made of aluminium. 5.The generator motor according to claim 1, wherein the casing of theterminal box comprises: a case detachably provided to the housing of thegenerator motor; and a cover member for closing an inner space of thecase with a seal member interposed between the cover member and thecase, wherein the casing is made of aluminium, and the cover member ismade of a steel material having a galvanized surface.
 6. The generatormotor according to claim 1, wherein an inside of the generator motor iscooled by a cooling medium.
 7. The generator motor according to claim 1,wherein the terminal box is attached to the generator motor at aposition lower than a top surface of the generator motor.
 8. Thegenerator motor according to claim 1, further comprising: a closingmember that closes the cable-insertion hole except for the cable.
 9. Thegenerator motor according to claim 1, wherein the terminal box houses aconnector for connecting the exterior electric-power-supplying cable tothe generator motor; and when the terminal box is connected to thehousing of the generator motor, the connector is disposed facingdownward and the electric-power-supplying cable is connectable to theconnector from underneath the connector.
 10. The generator motoraccording to claim 1, wherein the terminal box houses a plurality ofconnectors for connecting the exterior electric-power-supplying cable tothe generator motor; and when the terminal box is connected to thehousing of the generator motor, the plurality of connectors arejuxtaposed in a direction of the rotation shaft of the generator motor.11. A work machine comprising: a working equipment; a hydraulic pumpthat drives the working equipment; and the generator motor according toclaim 1, wherein the hydraulic pump is provided to the generator motor.12. The generator motor according to claim 6, wherein the cooling mediumcomprises a cooling oil.
 13. A generator motor connected to an outputshaft of an engine mounted in a work machine, the generator motorcomprising: a terminal box for connecting an exteriorelectric-power-supplying cable to the generator motor, the terminal boxhaving a casing that defines an inner space in communication with aninside of a housing of the generator motor; and a fixing portion forattaching the terminal box to the generator motor, wherein the fixingportion defines a cable-insertion hole that enables communicationbetween the inside of the generator motor and the inner space, anddefines a separate communication hole provided at a position verticallybelow the cable-insertion hole that enables additional communicationbetween the inside of the generator motor and the inner space, andwherein the casing of the terminal box is detachably provided to thehousing of the generator motor at a position that is vertically above arotation shaft of the generator motor.
 14. The generator motor accordingto claim 13, wherein the casing of the terminal box is made of amaterial having a lighter weight than that of a material for the housingof the generator motor.
 15. The generator motor according to claim 13,wherein the casing of the terminal box comprises: a case detachablyprovided to the housing of the generator motor; and a cover member forclosing an inner space of the case with a seal member interposed betweenthe cover member and the case, wherein the casing is made of aluminium,and the cover member is made of a steel material having a galvanizedsurface.
 16. The generator motor according to claim 13, wherein aninside of the generator motor is cooled by a cooling medium.
 17. Thegenerator motor according to claim 16, wherein the cooling mediumcomprises a cooling oil.
 18. The generator motor according to claim 13,wherein the terminal box is attached to the generator motor at aposition lower than a top surface of the generator motor.
 19. Thegenerator motor according to claim 13, wherein the terminal box houses aconnector for connecting the exterior electric-power-supplying cable tothe generator motor; and when the terminal box is connected to thehousing of the generator motor, the connector is disposed facingdownward and the electric-power-supplying cable is connectable to theconnector from underneath the connector.
 20. The generator motoraccording to claim 13, wherein the terminal box houses a plurality ofconnectors for connecting the exterior electric-power-supplying cable tothe generator motor; and when the terminal box is connected to thehousing of the generator motor, the plurality of connectors arejuxtaposed in a direction of the rotation shaft of the generator motor.